Does anybody know what salmon, or else herring, have to do with Yom Kippur?

Today I was asked, three times and with varying degrees of reproach, what had become of all of our chilled salmon. The last one said, “But there’s a Jewish holiday coming up! Why don’t you have more?”

At that point, I realized that the first two had also made references to needing the fish by Saturday, which my calendar says is Yom Kippur.